Plant-Inspired Dual-Functional Sensor for Monitoring Pulse and Sweat Volume

Wearable health monitoring sensors, when employed to monitor pulse and sweat volume in real-time during human physical activity, serve as an effective preventative measure against abnormal health conditions, such as elevated heart rate or excessive dehydration. Herein, a dual-functional sensor based on a sandwich structure composed of polyvinylidene fluoride hexafluoropropylene / conductive carbon black perforated film (named PCp film) and corncob sponge is designed to monitor pulse and sweat volume. The PCp film prepared by the breath figure method serves as a piezoresistive sensor with high sensitivity (0.06 kPa-1), a fast response time (0.9 ms), and high reusability for pulse monitoring. Furthermore, the PCp film has excellent water permeability (27.3 L m-2 h-1); thus, the sweat permeating through the PCp film can be absorbed by the corncob sponge. The sandwich-structured capacitive sensor is also highly sensitive (6.021 pF nL-1) to the absorbed sweat and is highly reusable. In addition, the dual-functional sensor is successfully integrated into a sports bracelet system to display real-time pulse and sweat-volume data of the wearer. This approach provides a dependable foundation for the advancement of multifunctional sensors in the field of sports monitoring. This paper presents a novel dual-functional sensor with a three-layer structure that can detect pulse and sweat volume. The upper and lower layers is perforated piezoresistive films, prepared using the breath figure method, which exhibits remarkable sensitivity, response time, and permeability. The middle layer is corncob sponge material, functioning as an equivalent capacitive sensor and demonstrating favorable humidity sensitivity. image